Parinaud syndrome

David Goldemund M.D.
Updated on 03/06/2024, published on 31/05/2024
  • Parinaud syndrome is caused by disturbance of the midbrain tectum and is characterized by upward gaze palsy, convergence retraction nystagmus, light-near dissociation, and bilateral lid retraction
  • syndrome is named after French ophthalmologist Henri Parinaud; synonyms: dorsal midbrain syndrome, Sylvian aqueduct syndrome, pretectal syndrome

Anatomy and pathophysiology

  • the vertical gaze center lies in the rostrodorsal portion of the midbrain and involves several key structures:
    • rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF)
    • the interstitial nucleus of Cajal (INC)
    • the nucleus of Darkschewitsch
    • the nucleus of the posterior commissure (involved in downward gaze)
    • oculomotor nucleus complex (CN III)
Rostral midbrain structures
  • Parinaud syndrome leads to upward gaze paresis due to riMLF and INC lesion; downgaze is relatively preserved; it is typically only affected by large space-occupying lesions or bilateral lesions
  • light-near dissociation (pupils accommodate but do not react to light) is due to damage to the pretectal and Edinger-Westphal nuclei or the decussating fibers of the pretectal nucleus in the posterior commissure
  • convergence-retraction nystagmus – due to abnormal burst activity in the pretectal area, causing intermittent co-contraction of the medial recti (convergence) + simultaneous superior and inferior rectus (retraction) during attempted upward gaze
  • bilateral lid retraction (Collier sign) due to loss of the supranuclear inhibitory input to the third nerve nucleus; the levator palpebrae superioris receives constant stimulation via the oculomotor nerve, resulting in lid retraction
  • riMLF is a crucial structure involved in the control of vertical eye movements
  • located in the rostral part of the midbrain, near the junction of the midbrain and the diencephalon, adjacent to the medial longitudinal fasciculus (MLF)
  • primarily responsible for initiating and coordinating rapid vertical eye movements (saccades)
    • receives inputs from various cortical and subcortical regions involved in the control of eye movements, including the frontal eye fields and superior colliculus
    • sends direct excitatory inputs to the oculomotor (III) and trochlear (IV) nuclei, which innervate the extraocular muscles responsible for vertical eye movements
  • riMLF works in conjunction with other nuclei, such as the interstitial nucleus of Cajal (INC), to integrate and execute vertical eye movements
  • lesions in the riMLF can lead to vertical gaze palsy, particularly affecting the ability to perform vertical saccades
  • INC plays a critical role in the control of eye movements, particularly in maintaining vertical gaze and contributing to the stabilization of eye position
  • it integrates signals from the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) for vertical saccades and smooth pursuits and is involved in the vestibulo-ocular reflex (VOR)
    • receives input from various brainstem structures involved in eye movement control, such as the superior colliculus and the riMLF
    • sends projections to the oculomotor and trochlear nuclei, which innervate the extraocular muscles responsible for vertical eye movements (superior and inferior rectus, superior and inferior oblique muscles)
  • the nucleus lies in the periaqueductal gray matter ventral to the aqueduct at the level of the superior colliculi
  • it has two major components:
    • a medially situated parasympathetic nucleus, the so-called Edinger-Westphal nucleus (or accessory autonomic nucleus), which innervates the intraocular muscles (the sphincter pupillae muscle and the ciliary muscle)
    • a larger and more laterally situated nuclear complex for four of the six extraocular muscles (the superior, inferior, and medial rectus muscles and the inferior oblique muscle). There is also a small nuclear area for the levator palpebrae muscle


  • ischemic stroke – occlusion of pretectal perforators or dorsal penetrating branches from the posterior cerebral artery (PCA) incl. quadrigeminal artery
    • vascular causes are more common among elderly populations
  • external compression (hydrocephalus, pineal tumors, aneurysm)
  • brainstem tumors (glioma), hemorrhage, or infections (e.g., toxoplasmosis)
  • multiple sclerosis
  • PSP
  • Whipple’s disease (GIT disturbances, dementia, uveitis)

Clinical presentation

  • upward gaze palsy (“sunset” eyes)
  • light-near dissociation
    • normal or slightly dilated pupils
    • no light reaction with preserved reaction to accommodation (pseudo Argyll-Robertson pupil)
  • convergence-retraction nystagmus during convergence
  • eyelid retraction (Collier sign)

Differential diagnosis

  • bilateral paralysis of the muscles elevating the eyeball (RS and Ol – “double elevator palsy”)
  • pseudo-dorsal midbrain syndrome in myasthenia gravis
  • local causes of upward movement limitation due to orbital lesions (thyroid eye disease, Brown’s syndrome of the superior oblique tendon)
  • congenital or age-related limitation of upward movement

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Parinaud syndrome